This sacred site forms part of a trio of holy wells in the Kilcar area, alongside Tobar Chonaill (St. Conall Caol’s Well) and Tobar Mhuire (the Blessed Virgin’s Well). The pilgrim’s circuit, or turus, traditionally begins in the ruins of St. Carthach’s old church, continues with three circuits around each of the three wells, and concludes at the altar in the church ruins. Curiously, whilst St. Carthach’s feast day falls on 5th March according to martyrologies, the local turus takes place on 4th March, possibly arranged to avoid conflicting with nearby St. Ciaran’s Well celebrations on the same date.

Local tradition holds that St. Carthach was a Munster bishop who travelled to this remote corner of Tirconaill to do penance for his sins. When his fellow Munstermen discovered his retreat and entreated him to return home, he refused. The historical connection between St. Carthach and his mentor St. Ciaran is reinforced by the proximity of their wells in this isolated region, a detail that appears to have escaped many hagiographical writers. Writing in 1936, Ó Muirgheasa documented the enduring popularity of these pilgrimage sites, noting the crowds that still performed the traditional stations despite some confusion in earlier Ordnance Survey Letters about which saints the wells commemorated.

The wider sacred landscape around Kilcar includes St. Patrick’s Well at Cashel on the north side of Towney Bay, though this no longer forms part of St. Carthach’s turus. Rather than marking a traditional missionary route from Ballyshannon, this well likely commemorates a brief boat journey St. Patrick made from County Sligo’s Tireragh district during fair weather, baptising converts before returning across the water. More intriguingly, Tobar Chnapostuin at nearby Muckress preserves not a Christian dedication but the memory of a fairy or ancient local deity, possibly representing a pre;Christian sacred well that escaped the attention of early missionaries and retained its pagan associations into modern times.